Oven or furnace



Aug. 1s, 192s 1,550,340

H. B. CAN NON OVEN OR FURNACE Filed May 14, 1924 3 Sheets-Sheet 1 Aug. 18, 1925. 1,550,340

H. B. CANNON OVEN OR FURNACE Filed May 14, 1924 s sheets-sheet 2 Aug. 18, 1925. 1,550,340

, H. B. CANNON i OVEN OR' FURNACE Filed May 14, 1924 3 Sheets-Sheet z5 kil IEM

vPatented Aug. V18, 19.25.,"-

Parleur oFFlcE.

HIRAM B. CANNON, OF METUCHEN, NEW JERSEY, ASSIGNOR OFONE-HALF T JOHN W. CANNON, OF BROOKLINE, MASSACHUSETTS.

ovEN Ion FURNACE.

Application led May 14,1924.l Serial No. 713,189.

To all 'whom t may concern:

Be it known that I; HIRAM B. CANNON, a citizen of the United States, residing at Metuchen, in the Icounty of Middlesex' and State of Ncw'J'ersey, have invented al certain new and useful improvement in Ovens or Furnaces, of which' the following is a full, clear, and exact description, reference being had t0 the accompanying drawings,

This invention relates t0 furnaces or ovens which are designed for the heating of articles out of direc-tcontact with products of combustion; and,.in the form disclosed herein, is particularly well suited for the heating l5 of enameled articles.

Y It is the general purpose and object of the invention to'v provide a furnace or oven of this character which is soeons'tructed and the parts of which are so arranged as to secure uniform heating of the .interior thereof, at--any temperature desired, within a wide range. A lfurther object of the invention is to enable the heating' of a furnace or oven of this character to be accomplished in a most eiiicient manner, in conjunction with radiant heat. A "further'and more limited object of the invention nace oneven of this character wherein the heating is accomplished by and in conjuncion With one or more interiorly heated combustion chambers forfiiied'piiincipally of material of high heatcon'dueting and lheatradiating qualities (such as .silicon carbide) and wherein the radiant heat froi such chamber or chambers is' utilized not y to heat uniformlythe interior of the furnace. or oven, but also to heat the hearth 'or floor thereof, which is alsoformed of material of high heat-conducting and heat-radiating 40 qualities, ,such as silicon carbide.y y

Further and still more limited objects of the invention will appear hereinafter and will be realized inand through the construc- Ition and arrangement of parts illustrated in the drawings, wherein Fig. 1 'is a transverse sectional View through a\furnace or oven constructed in accordance With my invention, the said view corresponding substantially to the line 1-1-of. Fig. 2; Fig. 2 a

5U longitudinal sectional viewthrough the furnace or oven shown inFig. l, the view corresponding to-the line 2-2 of Fig. l; Fig.

' 3 a-horizontal sectional view corresponding i to the line 3-3 of Fig. l; andFig. 4 a secis -to provide a fur.- f

are discharged into a tional View corresponding-to the line 4-4 of Fig. l.

Describing the various parts by reference characters, 1 denotes generally the furnace setting, which may .be of any ordinary or standard material, the Walls of the setting being shown as strengthened by the vertical structural beams 2 connected in pairs by tie rods 3 extending through the furnace structure and connecting opposed pairs of such beams. The furnace or oven disclosed herein is one which is suited for of porcelain enameled Ware and one whereinto the Work may be inserted and wherefrom it may be removed by means of a fork, the oven in this case being semi-continuous. The front or charging opening of the oven is indicated at 4 and is provided with a door 5 communicating with the heating chamber 6.

The heating chamber is comprised generally between a hearth 7, side Walls, 8, a rear Wall 9, a front wall 10, and an arched roof 11.

The walls -8 incline upwardly and outwardly from refractory brick-Work piers 12 Which extend above the hearth 7, at each side thereof, and form each a support for 'a combustion chamber, the chambers being indicated generally at 13.

Each combustion.chamber comprises a bottom wall 14 which is, supported upon a pier 12, the bricks whereof are spaced apart,

as shown in Fig. 2, to provide for the cir- 'culation of air and to assist in producing a uniform temperature within .the working space of thepfurnace or oven. The bottom Wall 14 ofeach combustion chamber is provided With an outlet 14a at the front thereof through which the products of combustion downwardly extend- -ing flue 14b which vcommunicates with the space forming' aflue beneath the hearth 7 the details of Which flue will be described hereinafter` Each combustion chamber comprises, in addition to the bottom Wall 14 and he outlet 14a, a top Wall 15 extending forwardly beyond the bottom Wall, both the top and thebottom wall extending rearwardly t0 a point adjacent to but spaced from the rear Wall 9 of the oven. 16 denotes the rear Wall ofeach combustion chamber and 17' the side Walls. These side walls are provided, at approximately midheight thereof, With grooved seats for a horizontal par the baking l tition 18, which eXtends from the front of the combustion chamber rearwardly toward, but spaced from, the rear wall 16, thereby providing passagesabove, around and below the said partition. In front` of the opening 14 a slab 19, preferably@ of silicon carbide, closes the front end of the lower passage.. The upper passage projects forwardly beyond the lower passageway and registers with a neck or extension, such neclr or extension being indicated at .2() and within whichl and arranged axially thereof. is the front or delivery end of a burner 21.

Extending from the flue 14b forwardly through the furnace wall is a sight opening 22. the outer end of which will be closed or sealed hy a disk 22u of suitable material, such as mica.

The combustion chambers described herein are of the same general type as setI forth in Patent No. 1.371.774 granted to Hiram B. Cannon March 15. 1921.and. as is the case with the combustion chamber of said patent. each is composed principally of silicon carbide. because of the high .heatradiating and heat-conducting qualities of such material.

The combustion are arranged to be suitable fluid fuel, the said burners being mounted each in a wind boxv 23 each inserted within the front wall of the furnace structure. Each burner is provided with a supply pipe 24 for oil, or other similar combustible fluid. and a supply pipe 25 for air or other fluid under pressure for the purpose of atomizing such oil. In addition, each wind box has connected thereto a pipe 26 supplying a secondary supply of air for the purpose of completing the combustion of the fuel thus atomized. The pipes 24. 25 and 26 are provided with valves 24, 25*L and 26,a for controlling the How of their respective iuids therethrough. I

Each of the com ustion chambers 13 is supported by its nier 12' adiacent to but spaced from the inclined side wall 8 of the furnace or oven. Inv order to prevent uneven. excessive. and inefficient heating of the articles within the space between the chambers shown herein heated bv oil. or other said combustion chambers, a screen or bafHe 27 is interposed between each such combustion chamber and the central portion of the furnace. the screens or baffies beinglocated in fairly close proximity to their respective combustion chambers and extending parallel therewith and, from the front to the rear of the oven or furnace chamber. The hearth 7 extends across the space between the screens or baffles 27 and is preferably made of material having high heatradiating and high heat-conducting qualities. such as silicon carbide.

Reference has been made heretofore to -the piers 30", 30";

through the burners 21,

the downtake iiues 14h and to the space or flue beneath the hearth with which these iiues communicate. This space orl flue will nowbe described, with particular reference to Figs. 2 and 8.

The hearth 7 covers a chamber therebeneath, indicated generally at 28 and having side walls 28, a bottom wall 28b and a rear wall 28C, the hearth constituting a top or cover for said chamber. The chamber'28 comprises also a front transverse passage 29 with the opposite ends whereof the flues 14h communlcate. The passage 29 1s formed between the front wall of the furnace and a pair of piers 30 projectingr toward each other from the side walls 28 and providing a short passage 29a therebetween. 30 and 30*denote additional pairs` of piers, arranged similarly to the piers,

30 and interposed between sa1d piers 30 and the rear wall 28c and being spaced preferably equidistantly between the piers 30 and from the said wall. Piers 31 are lo cated midway between the piers 30, 30 and the adjacent piers 30, 30a; piers 3,1a midway between t-he last mentioned piers and and piers 31b midway between these piers and the rear wall 28C. Each of the piers 31 extends transversely of the chamber 28, with its ends spaced from the side walls 28a thereof to provide lateral passages around such ends.

lVith this, construction and arrangement vof piers 3030b, it will be evident that products of combustion delivered from the flues 11b will' flow inwardly through the passage 29, then rearwardly through the passage 29a, around the ends of the pier 31 and through the passage between the piers 30, around the end of the pier 31a, through the passage between the piers 30", around the ends of thel pier 31h, and thence from the flue formed by said passages, through the central iue 32 to the stack A33.

Where oil is used as fuel, it is preferred to place a wedgeshaped baffle 34 adjacent to the delivery end of the burnerabout six inches therefrom, as such bafliel serves to secure the early ignition of the incoming fuel and modifies the gas pulsations resulting from combustion.

Reference has been made hereinbefore to the upward and outward inclination of the side walls 8 and to the arched construction of the roof 11. These parts are designed with special reference to securing a maximum and uniform heating efficiency from the radiatingA combustion chambers 13, This particular slope of the side walls, with the particular rise and curvature of the arch. permits of a high-degree of transfer of heat by radiation from the tops of the combustion chambers and from the sides thereof which face the walls 8. They heat thus radiated is reflected from/the sloping walls in accordance With thereto from the combustion chambers.

The hearth, being made of refractory mahigh heat,conductivity (such.

terial having as silicon carbide) permits of the rapid How of radiant heat from the arch and in turn radiates the heat received by it to the material of which the piers 30-31b and the bottom lining of the flue passages beneath the hearth are composed, such material being` preferably a refractoryvmaterial having low heat-conductivity and high heatstoring properties, Furthermore, each combustion chamber is spaced at the pro er distance from the sloping side Wall 8 adjacentthereto to insure the proper exposure of such side Wall to the adjacent radiating side of the combustion chamber, thereby to secure a maximum transfer of radiant heat from such' chamber side Wall.

The battles or screens 27 are made of refractory material. and are 'preferably perforatcd, as indicated at 27a, belcwi the top` it being preferable that at least the bottom portions'of the baflles or screens shall be provided with openings or perforations in order to permit of the equalization of the temperature of the atmosphere Within the furnace or ovjen. The materialV of Which these balies o-r screens is composed will vary the work to be done. It is their purpose to screen or shield the ar-r ticles above the hearth 7 from a too4 concentrated radiant heat emanating from the side Walls of the combustion chambers. For

the majority of purposes at present'v in view,

the baiiles or screenswvill `be made of a refractory-material having high heat conductivity (suchA as silicon carbide); and theirl height will be such asto. prevent a direct exposure of the Work to the radiant heat from the combustion chambers. In porcelain enamel-Work, Where the temperature may range from 1600O to 1900o F., and Where uniform temperature conditions are required Within the' working s ace -of lthe oven or furnace, it has been ound that the baffles or screens `27 should be'made of silicon carbidef brick andA that the height of said baffles or lscreens should-be such that the surfaces of the combustion chambers will not be exposed to the Work Within 'the oven. In this case, thebales or screens act each as a reducing valve for the radiating surfaces of the combustion chambers `exposed respectively thereto, the baille Walls transferring to the work a reducetl'amount of radiant heat (as compared With the radiant heat from the respective combustion chambers), with the result that the Working space Within the oven is brought to tem erature.

- I en desirable, the -transfer of radiant yreach the a very uniformor screens and the heat reflected heat from the baffles or screens 27 may be increased by making the said baiiles or screens higher, which will also result in4 reducing the transfer of radiant heat from the taps of the combustion chambers tothe arch' and eren from the outer sides of the combustion chambers, through the sloping ivalls 8 (depending upon the height of the battles Aor screens To the extent to which the height of the bafilcs or screens is increased, the surface temperatures of thecombustion cham- `bers willbe increased, v-with a correspondingly increased transfer'of radiant heat to the baiiles or screens and from the latter to the Working space therebetween.

. W'here the baliles or screens are made. of refractory material of low heat-conductivity and of a'height vsuiiicicnt to prevent direct exposure of the 'Work tothe radiating surl faces of the combustion chambers, the heat' 85 which is radiated to the worlrfrom ythe baflies or screens will be diminished, Wit-h the result that more heat Will be radiated fromy the outer sides and the` tops of the combustion chambers to the Walls 8 and the arch, 90 and from thearch to the Work, to the hearth 7 and to the linings of the flue passages beneath the latter.- 1- j f l Should the baiiies or screens of lowheatconductivity be built to a sufficient height to arch, then the greater portion of the heat due toA combustion would be delivered as sensible heat to the exhaust. 2 "ases underthe hearth, the balies or screens receiving and radiating' a definite amount yof 100 heat. In this case, however, the radiant heat transferred to the Working space would be entirely from the hearth and from the ybaffles or screens.

For most purposes, it is preferable to use material of high heat-conductivity for the bailles or screens and to make them of a. height which Will interceptv radiant heat from the sides of the combustion chambers adjacent thereto. Under theseconditions, when the liamefrom each combustion chamber just reaches the -outlet D (which may bc accomplished by a suitable regulation of the fuel and air, in lconjunction With the peepholes 22), the hearth will receive only a 115 limited amount of heat by convection from the exhaust gases.J j In this case, when no Work is Within the oven, the radiant heat from the outer side of each combustionf chamber Will be reflected sloping side Walls to the arch. Thisvr re.. flected-heat, .together with the heat radiated to the arch from the tops of the combustion chambers, will Tbe reflected by thex'arch to the hearth and will be radiated from the latter to and stored in the supporting piers and in the bottoms of the Hue passa-ges ther@ under. When Work is inserted into the chamber, it is heated, not only by the baffles from the bjr the adjacent 120 I arch, but also by mea-ns of radiant heat from the hearth which has been 'previously reflected thereto from the arch and stored thereunder.

Having thus described my invention, what claim is I,

1. A furnace or oven comprising in combination a hearth with a heating chamber thereabove, a combustion chamber within the first-mentioned chamber, means for supplying a combustible mixture tothe combustion chamber for heating the latter interiorly, there being a flue below said hearth, and means for discharging the products of combustion from said chamber into saidlflue and beneath said hearth, the said hearth being composed of material having high heat-radiating qualities.

2. A furnace or oven comprising in combination a hearth with a heating chamber thereabove, a combustion chamber within the Erst-mentioned chamber, the said combustion chamber being provided with upper and lower passages communicating` at the inner or rear end of such chamber, there being a discharge outlet from the lower passage adjacent to the front of said chamber, and means for delivering a combustible mixture to the front of the upper passage, there being a flue or chamber beneath said hearth with which the said outlet communicates, the combustion chamber and the hearth being formed of material having high heatradiating qualities.

3. A furnace or oven comprising in com bination a hearth with a heating chamber thereabove, there being a flue beneath said hearth and supports-for said hearth, a com-- bustion chamber within the rst-mentioned chamber, the said combustion chamber comprising top, bottom, side and rear walls, with a partition extending from the front wall,

.between the top and bottom walls, toward andspaced from the rear wall, the front of the passage formed below thesaid partition communicating with the said iue, and ineans for delivering a combustible mixture to the front of said combustion chamber, above the partition, the said combustion chamber and the said hrth being composed of material' having high heat-radiating qualities.

4. A furnace or oven comprising in combination a hearth with a chamber thereabove, there being a flue beneath said hearth and supports for said hearth, a combustion chamber within the rst mentioned chamber,

the said combustion chamber comprising top,

bottom. side and rear walls, with a partition extending from the front wall, between the top and bottom walls, toward and spaced from the rear wall, the front of the passage formed below the said/partition communieating with the said flue, and means for deliveringa combustible miXture'to the front of said combustion chamber, above the partition, the said said hearth said supports being compose being composed ing high heat combustion chamber and the and the heat-absorbing qualities.

5. A furnace or oven c of material hav- -radiating qualities and the bottom of the flue d of material having high omprising a hearth of material of high heat-radiating qualities with a heating chamber therea bustion chamber o radiatlng qualities 1n t hearth,

the said combust bove, a comf material of high heathe chamber above said ion chamber being arranged to heat the space adjacent the hearth by radiant heat, and means for conducting the products of combustion from the said combustio hearth thereby to heat the latter by means of the sensible G. A furnace bination a heating chamber of high within the hea said combusti heating the first mentio n chamber beneath the said heat in such products.`

chamber,

ting chamb on chamber,

or oven comprising in coma combustion heat-radiating qualities er, means for heatchamber iirst mentioned chamfrom a portion of the and meansfor ned chamber by reinteriorly,

flected radiant heat from other portions of lsaid combustion chamber.

7 A furnace or ov w ith en comprising inVV cdmbination a hearth of high heat-radlating a iiue therebeneath and a heating chamber above the said hearth, a

combustion qualities above communi riorly,

the Vspace chamber of high heat-radiating said hearth and having an leating with said iue, means for heating the combus means for heating tion chamber intethe said hearth and thereabove by radiant heat from a part lof said combustion chamber, and

means for heatin `said space by other portions 8. A -furnace bination a heating chamber, a combustion heat-radiating qualities amber, means for heatchamber of high within the heating ch `ing the combustion heat-radiating s'aidjcombustion first mentioned part from direct ra o' the said he arth and the reiected radiant heat4 from of said combustion chamber.

chamber screen mterpo or oven comprising in cominteriorly, a sed between chamber and a part of the' chamber and shielding such diant heat from the portion of-the combustion chamber adjacent thereto, and means heat from other por chamber to such par chamber.

heat-radiating 9. A furnace or oven comp bination a heating chamber, chamber of' high heat-rad within the heating chamber, ing lthe combustion for retiecting the radiant tions of said combustion t of the first-mentioned rising in coma combustion iating qu means for heatchamber interiorly, a

alities screen interposed between said mentioned chamber and shieldi part of the first ng such partfrom direct radiant heat from the portion of the combustion chamber adjacent thereto, a hearth of high heat radiating material at the bottom of the aforesaid part of the first .mentioned chamber and having a flue thereunder with which the outlef` from said combustion chamber communicating and means for reflecting the radiant heat from other portions of saidicombustion chamber to such part of the firstimentioned chamber and to the hearth. A -l 10. A furnace or oven comprising in combination a heating chamber, a pair of co1nbustion chambers of high heat-radiating qualities and spaced apart within the first mentioned chamber,n means for heating the said combustion chambers interiorly, means for heating the space between such combustion chambers by' radiant heat from the portions of the combustion chambers adjacent thereto, and'mea-ns for heating such space by heat reflected from other portions of said combustion chambers. v

11. A furnace or oven comprising in combination a heating chamber, a pair of co1nbustion chambers of high heat-radiating qualities and spaced apart within the rst mentioned chamber, means for heating the said combustion chambers interiorly, a. hearth of highv heat-radiating qualities at the bottom of the spacebetween said combustion chambers .and having a flue or chamber therebeneath, means for heating the, space between such combustion chambers and the hearth by radiant heat from the portions of the combustion chambers adjacent thereto, means for heating such space and hearth by heat reflected from the other portions of said combustion chambers, and means for discharging products of combustionl from the said combustion chambers into the said flue or chamber beneath said hearth.

12. A furnace or oven comprising in combination a heating chamber, a pair ofcombustion chambers of high heat-radiating qualities spaced apart within the first mentioned bhambers, means for heating the said combustion chambers interiorly, a screen of heat-radiating material interposed between each combustion chamber and the space therebetween, Aand mea-ns for ,heating such space by reflected radiant heatfrom portions of said combustion chambers'which are not adjacent to said screens.

13. A furnace or oven comprising in combination a heating chamber, a pair of combustion chambers of high heat-radiating qualities spaced apart within'said heating chamber, means forburning a combustible mixture within the said combustion chambers, a hearth of high heat-radiating qualities at the bottom of the space between said combustion chambers, means for discharging products of combustion from the combustion chambers into the flue or chamber beneath said he'arth, a [screen of radiating material interposed between each combustion chamber and the space and the hearth therebetween, and means for heating suoli space and hearth by reiiected radiant 'heat from the portions of the combustion chamberswhich are not adjacent to said screens.

14. A furnace or oven comprising in combination a hearth with a chamber thereabove, there being a flue and supporting piers for said hearth beneath the latter, a combustion chamber on each side of the firstmentioned chamber,` above said hearth, and each having an outlet communicating with the iiue beneath the hearth, means for refleeting" ytoward the hearth heat radiated from the outer walls and the tops of said combustion chambers, the said combustion chambers and the said .hearth being composed of material having high heat-radiating qualities and the piers and the material constituting the bottom of the Hue possessingy high heat-absorbing qualities.

15. A furnace or oven comprising in combination a hearth'with a chamber thereabove, there being a flue and supports for said hearth beneath the latter a combustion chamber oneach side of the rst-mentioned chamber, above said hearth, and each having an outlet communicating with the flue beneath the hearth, means for reecting toward the hearth heat radiated from the outer walls and the tops of said combustion chambers, the said combustion chambers and the said hearth being composed of material of high heat-radiating qualities and the supports andthe material constituting the lbottom of the flue possessing high heat-absorbing qualities, and a screen interposed between each combustion chamber and the space above said hearth.

16. A furnace or oven comprising in combination a hearth with a chamber therel above, there being a iiue and supporting possessing high heat-absorbing qualities,

and -a ,baiiieor screen interposed between each combustion chamber and the space above said hearth, the said screen being composedof material possessing heat-radiating qualities.

17. A furnace or oven comprising in combination a hearth of heat-radiating material having a flue therebeneath and piers for supporting the said hearth, with a chamber above said hearth, a combustion chamber of material having heat-radiating qualities arranged in the said chamber, on each side of the said hearth, means for heating the said combustion chambers interiorly, means for circulating the products of combustion from said chambers through the said flue, means for shieldingthe space above said hearth and between the said combustion chambers from the portions of the combustion chambers which are adjacent to such space, and means for reflecting to such space Vthe heat radiated by the other portions of such combustion chambers.

18. A furnace or oven comprising a hearth of high heat-radiating material, with a chamber above said hearth, a combustion chamber in the first mentioned chamber and located at each side of said hearth, the said combustion chambers being composed of material of high heat-radiating qualities,"means for heating the said combustion 1chambers interiorly and for circulating the products of combustion therefrom beneath the said hearth,"a heat-radiating screen interposed between each combustion chamber and the space above the hearth, each of said screens being arranged to be heated by radiant heat from the combustion chamber adjacent thereto, and means for reflectinginto the space above said vhearth heat radiated from the parts of the combustion chambers which are not immediately adjacent to the said screens.

19;l A furnace or oven comprising in combination an arched roof,\upwardly and outwardly sloping sides, and a bottom provided with a hearth, there being a flue beneath the said hearth and supporting piers for said hearth, a combustion chamber on each side of said furnace, extending longitudinally thereof and adjacent to the cooperating side Wall, each of said chambers being composed principally of material having high heat-radiating qualities and each having an outlet communicating with the iiue beneath the hearth, a screen extending longitudinally of the said furnace adjacent to each combustion chamber and between the same and the central portion of the furnace chamber,`and means for'supplying a combustible mixture Yto each combustion chamber, the said hearth being composed of material having high heat-radiating qualities.

20. A furnace or oven comprising in combination a roof, sides, and a bottom provided with a hearth, there being a flue beneath the said hearth and supports for said hearth, a combustion chamber on each side of said furnace, extending longitudinally thereof and adjacent to the cooperating side wall, each of said chambers being composed of material having high heat-radiating qualities and each having an ontlet commu-l nicating with the iiue beneath the hcartha screen extending longitudinally of the said l portion of thefurnace chamber, and means for supplying a combustible mixture to each combustion chamber, the said hearth being composed of material having high heat-radiating qualities and the sides and roof of the furnace or oven being arranged to reflect radiant heat from the combustion chambers toward the hearth.

2l. A furnace or oven comprising in combination an arched roof, upwardly and outwardly sloping sides, and a bottom provided with a hearth, there being a flue beneath the said hearth and supporting piers for said hearth, a combustion chamber on each side of said furnace, extending longitudinally thereof and adjacent to the cooperating side wall, each of said chambers having an -oiitlet communicating with the iiue beneath tlie hearth, a screen extending longitudinally of the said furnace adjacent to each cornbustion chamber and between the same and the central portion of the furnace chamber, means for supplying a combustible mixture to each combustion chamber, the said combustion chambers and the said hearth being composed of material of high heat-radiating qualities and the said piers and the material constituting the bottom of the flue being material possessing high heat-absorbing qualities.`

Q2. A furnace or oven comprising` in conibination an arched roof, upwardly and outwardly sloping sides, and a bottom, a combustion chamber onveach side-of said furnace, extending longitudinally thereof and adjacent to the cooperating side wall, each of said chambers being composed of material having high heat-radiating qualities., a screen extending longitudinally of the said furnace adjacent to each combustion chamber and between the same and the central portion of the furnace chamber, and

means for heating each combustion chamber interiorly.

23. A furnace or oven comprising in com` bination an arched roof, upwardly and outwardly sloping sides, and a bottom provided with a hearth, there/being a flue beneath the said hearth and supports for said hearth, a combustion chamber on each side of said furnace, extending longitudinally thereof and adjacent to the cooperating side wall, each of said chambers being composed of material having high heat-radiating qualities and each having an outlet communicating with the flue beneath the hearth, a screen extending longitudinally of the said furnace adjacent to each combustion chamber and between the same and the central portion of the furnace chamber, means for supplying a combustible mixture to each combustion chamber, the said"hearth and the said screen being composed of materialhaving high heat-radiating qualities and the said supports and the material constituting the bottom of the flue being material possessing high heat-absorbing`qualities.

24.. A furnace or oven comprising in combination an arched roof, upwardly and outwardly sloping sides, and a bottom, a combustion chamberon each side of said furnace, extending longitudinally thereof and adjacent to the cooperating side wall, each of'said chambers being composed of material of high heat-radiating qualities, means for heating each combustion chamber interiorly, a screen extending longitudinally of the said furnace adjacent to each combustion chamber and between the same and the central .portion of the furnace chamber, the said screens being composed of material of high heat-radiating qualities. y 25. A furnace, comprising a heating chamber, a combustion chamber having a silicon carbide partitioning Wall between it and the heating chamber, and a baiiie wall between said combustion chamber and the space occupied by the material being heated, substantially as described.

26. A furnace, comprising a heating chamber, a combustion chamber having aV silicon carbide partitioning wall between it and the heating chamber, and a silicon carbide baiiie wall between said combustion chamber and the space occupied by the material being heated, substantially as described.

27. A furnace, comprisin a heating chamber, a combustion cham r having a silicon carbide partitioning wall between it and the heating chamber, and a baile wallbetween said combustion chamber and theV space upied by the material being heated, said b e wall being formed with open bide baiiie Wall `between said combustion chamber and the space occupied by the mate- -rial Abeing heated, said baliie wall being formed with open spaces permitting direct radiation fromv the combustion chamber to said material, substantially as described.

29. A furnace, comprising a heating chamber, a combustion chamber having a silicon carbide. partitioningwall between it and the heatingchamber, a silicon carbide baffle Wall between said combustion chamber and the space occupied by the material being heated, and a waste heat flue beneath the Hoor of said heating chamber and .having its top wall formed thereby, said top wall being'constructed of silicon carbide, substantially as described. 30. A furnace, comprising a heating chamber, a combustion `chamberhaving a silicon carbide partitioning wall between it and the heating chamber, a bale wall between said Acombustion chamber' and the space occupied by the material being heated, and a waste heat flue beneath the ioor of said heating chamber and in heating relation therewith, substantially las described. v A

In testimony whereof, I hereunto aiix my signature.

Bj cANNoN. 

